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Thread: HELP Pump problems Cavitation?

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    HELP Pump problems Cavitation?

    Howdy-

    First off, after reading lots of forums, the members here seem to be on the ball. So thanks to all...

    I just replaced a Pentair CCP320 that was falling apart with a Hayward S244T with zeobest as recommended by large pool chain. Started up and backwashed for while till clear, rinsed and then went to filter. After about 5 minutes, it still sounds like lots of air bubbling, actually sounds like marbles in tank at top near valve. All fittings tight and no noticable leaks. Returns show no bubbling so I'm at a loss?? With the CCp320, i'd just turn the pressure relief on top and all was good.

    Here is the set-up that might be adding to problem. All plumbing is 2" right up to 7 port top mount valve which is fitted with 1-1/2" intake/ outflow. Pump is a 2HP Pentair whisperflo. All plumbing is real clean with no bends from pump to filter and then out two 45' bends to heater.
    Pool is 16x32 6.5 ft deep end. Anybody have any ideas? Pump to big? Downsize impeller? Reduce plumbing to 1-1/2" from pump to filter?

    Thanks to all for your help..

  2. Back To Top    #2
    Mod Squad JohnT's Avatar
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    Re: HELP Pump problems Cavitation?

    Welcome to TFP.

    Your pump is too big, but I wouldn't expect it to cause your noise. Can you loosen the pressure gauge slightly to vent the air?
    TFP Moderator
    20K Gallon 20X36 Vinyl Inground
    Hayward S244T Sand Filter with 1HP Whisperflo Pump. Liquidator C-201 and Solar Heat

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    mas985's Avatar
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    Re: HELP Pump problems Cavitation?

    First welcome to the forum. Second, a few questions to add to John's:

    Is the filter pressure any different with the new vs old filter?

    Do you see any air bubbles in the pump basket? If so, are the small or large?

    Are there multiple suction lines or a single line to the pool?

    It sounds like you are getting some air in the filter but it does not come out of the returns so it must not accumulate. Have you let the system run for some time to see if it is just trapped air in the new media?
    Mark
    Hydraulics 101; Pump Ed 101; Pump and Pool Spreadsheets; Pump Run Time Study; DIY Acid Dosing; DIY Cover Roller
    18'x36' 20k plaster, 1/2 HP 2sp pump, Aqualogic PS8 SWCG, 420 sq-ft Cartridge, Solar, 6 jet spa, 1 HP jet pump, 400k BTU NG Heater

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    Re: HELP Pump problems Cavitation?

    Thanks for some ideas! Yes, the pressure is running about 22PSI and gauge bounces, I was about 14PSI with clean filters. I attributed the higher pressure to restriction from 2" to 1-1/2" at valve. Pump has run about 7 hrs and is still making noise. I do not see bubbles in pump basket. I have 2 skimmers and 1 main drain. I am going to try and bleed off thru gauge when I get home. If I get new 1.5 hp pump/motor, am I going to have problem again with plumbing? i.e. 2" to 1-1/2 at pump?

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    mas985's Avatar
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    Re: HELP Pump problems Cavitation?

    The reduction to 1 1/2" at the filter would not have that much effect (< 1 PSI). But going from 14 PSI in your old filter to 22 PSI with your new filter is a significant change and would certainly indicate a problem with the filter. Filters really shouldn't add that much head loss.

    But as John pointed out earlier, that pump is way too big for that size filter. The S244T is rated for only 62 GPM which a 2 HP pump is likely to well exceed. Pretty much any pump will exceed that except for maybe a 1/2 HP. Your old filter had a rating of 120 GPM which is fine for that size pump. So the pump flow rate is likely causing problems with the internals of the filter and may even be damaging the filter. I suspect what you are hearing is the zeobest bouncing off of the housing much like a sand blaster. Zeobest is lighter than sand and so more likely to be moved by high flow. But even with sand, you would have a problem.
    Mark
    Hydraulics 101; Pump Ed 101; Pump and Pool Spreadsheets; Pump Run Time Study; DIY Acid Dosing; DIY Cover Roller
    18'x36' 20k plaster, 1/2 HP 2sp pump, Aqualogic PS8 SWCG, 420 sq-ft Cartridge, Solar, 6 jet spa, 1 HP jet pump, 400k BTU NG Heater

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    Re: HELP Pump problems Cavitation?

    Thanks for the info. Sounds like a 1 hp is the way to go. just concerned that I will lose jet pressure but I can reduce eyeball to smaller from 1" that I have now and gain a little there. For plumbing, is it ok to have 2" to pump basket, 1-1/2 from pump to filter and then go back to 2" return thru heater? Sorry for all questions, new to this and still learning... Before I buy new pump tonite, I guess that 1.5 hp is still too much?

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    Re: HELP Pump problems Cavitation?

    Mark-

    Thanks again. The sound is right at top at valve and not really in filter housing. The valve seems to function fine with no leaking or difficulty in moving thru settings. But at this point I will try anything and yes I thought the pump was too much HP but the big box pool co said "sure no problem we d o it all the time!!!" Lesson learned. I just wish I found this site first.

    Best regards!

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    mas985's Avatar
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    Re: HELP Pump problems Cavitation?

    Even a 1 HP can be too much depending on the pump. A 1 HP Superpump might be ok but will probably still exceed 62 GPM. What brand/model # pump are you looking at? What is the current pump model #? Another option is to just replace the impeller and maybe the diffusor with the smallest one available for the pump line. This is very cheap to do and would allow you to see any benefits without significant costs.

    Also, how many return eyeballs do you have? Reducing the eyeball size will increase filter pressure but it will also decrease flow rate and in your case may be a good thing. Unfortunately, it also reduces the efficiency but that is probably less important than preventing damage to your filter.

    BTW, I forgot to ask, are your running spa jets with this same pump?
    Mark
    Hydraulics 101; Pump Ed 101; Pump and Pool Spreadsheets; Pump Run Time Study; DIY Acid Dosing; DIY Cover Roller
    18'x36' 20k plaster, 1/2 HP 2sp pump, Aqualogic PS8 SWCG, 420 sq-ft Cartridge, Solar, 6 jet spa, 1 HP jet pump, 400k BTU NG Heater

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    Re: HELP Pump problems Cavitation?

    Mark-

    I am running a 2hp Pentair whisperflo not sure of part # but can check in 30 minutes when I get home from office. I was thinking a Hayward 1hp superpump? At Leslie's for $350 can order on line for 290 but can't wait due to holiday coming up. I have 4 returns 1 low end 1 deep end and 2 on steps but no air control or spa feature. I think downsizing pumo motor is good idea due to energy savings. Mine is 5 + years old now.

    Thanks again

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    mas985's Avatar
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    Re: HELP Pump problems Cavitation?

    You can certainly purchase a new pump but if you want the performance and energy efficiency of a WFE-2 Whisperflo (1/2 HP), you could just change the impeller of your current pump. Assuming you have a WFE-8 now, and by replacing the impeller with this, you would improve the overall efficiency of the pump by close to 35% in terms of gallons/watt-hr pumped. 5 years is not that old for a pump and the housing probably has many years left in it. Later, you can then think about replacing the motor perhaps with a two speed for even more savings.

    The power consumption and energy efficiency of a pump is determined by the impeller load and motor efficiency and not by the actual HP rating of the motor. The good thing about high HP rated motors is that they are more efficient than low HP rated motors. So even though you would be under loading the motor by quite a bit, the efficiency of the pump would still be quite good and not much different from the efficiency of a WFE-2. So you would get most if not all the energy effiiciency benefit of a new pump without the added cost.

    Also, if you change out the pump entirely, especially with one of a different manufacture, you will also need to change at least part of the plumbing. With just an impeller change, everything else remains the same and can usually be done without any plumbing work. Just something to think about when making your decision.
    Mark
    Hydraulics 101; Pump Ed 101; Pump and Pool Spreadsheets; Pump Run Time Study; DIY Acid Dosing; DIY Cover Roller
    18'x36' 20k plaster, 1/2 HP 2sp pump, Aqualogic PS8 SWCG, 420 sq-ft Cartridge, Solar, 6 jet spa, 1 HP jet pump, 400k BTU NG Heater

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    Re: HELP Pump problems Cavitation?

    Mark-
    Thanks again. I have a WF-28 2HP. If I change to the 1/2 HP impeller, how will that effect the return lines? I would think that the pressure is going to drop off at the low end jets which are 45 feet approx. from filter. I read thru Hydraulics 101 and ???

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    mas985's Avatar
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    Re: HELP Pump problems Cavitation?

    Yes the pressure and flow rate will drop off some with a 1/2 HP but that should not be a problem. Currently, I am running a 1/2 HP (2 speed) with a 20k pool and 4 returns. On full speed, there is plenty of flow rate for the skimmers to work properly.

    Do you also need to run a cleaner? I had to adjust the suction on the cleaner some but is still works fine.

    The WF-28 is an uprated pump so it is similar to the 1 1/2 HP full rated WF-6. If you swap out the impeller here is what you might expect:

    WF-28; 22 PSI, 62' head, 84 GPM, 2253 watts

    WF-2; 13 PSI, 38' head, 64 GPM, 1386 watts (impeller change only)

    You would need to run the pump about 30% longer but overall, you would use 20% less energy even with the longer run time.
    Mark
    Hydraulics 101; Pump Ed 101; Pump and Pool Spreadsheets; Pump Run Time Study; DIY Acid Dosing; DIY Cover Roller
    18'x36' 20k plaster, 1/2 HP 2sp pump, Aqualogic PS8 SWCG, 420 sq-ft Cartridge, Solar, 6 jet spa, 1 HP jet pump, 400k BTU NG Heater

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    Re: HELP Pump problems Cavitation?

    Mark-

    Yes I am running a hayward vac. How do I adjust for that? Currently I close 1 skimmer and the MD a little. I just ordered the 1/2hp impeller and also a PS1000 mech seal for same.

    Thanks for all of your help!

    Tim

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    mas985's Avatar
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    Re: HELP Pump problems Cavitation?

    You may find out that you will just need to close the main drain a little bit more than you did before when vacuuming.
    Mark
    Hydraulics 101; Pump Ed 101; Pump and Pool Spreadsheets; Pump Run Time Study; DIY Acid Dosing; DIY Cover Roller
    18'x36' 20k plaster, 1/2 HP 2sp pump, Aqualogic PS8 SWCG, 420 sq-ft Cartridge, Solar, 6 jet spa, 1 HP jet pump, 400k BTU NG Heater

  15. Back To Top    #15

    Re: HELP Pump problems Cavitation?

    Mark-

    Sorry for delay!! It all works great. Good flow approx 14 psi and quiet too! Thanks for all of you time. Hope you had a great weekend, I finally did.

    THANKS AGAIN!!

    Tim

  16. Back To Top    #16
    mas985's Avatar
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    Re: HELP Pump problems Cavitation?

    I'm glad it worked out for you. If you can, please let me know what the power draw is.
    Mark
    Hydraulics 101; Pump Ed 101; Pump and Pool Spreadsheets; Pump Run Time Study; DIY Acid Dosing; DIY Cover Roller
    18'x36' 20k plaster, 1/2 HP 2sp pump, Aqualogic PS8 SWCG, 420 sq-ft Cartridge, Solar, 6 jet spa, 1 HP jet pump, 400k BTU NG Heater

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